Facemash attracted 450 visitors and 22,000 photo-views in its first four hours online.

Zuckerberg wrote a program called Facemash on October 28, 2003 while attending Harvard University as a sophomore (second year student).

According to The Harvard Crimson, the site was comparable to Hot or Not and used "photos compiled from the online facebooks of nine houses, placing two next to each other at a time and asking users to choose the 'hotter' person" To accomplish this, Zuckerberg hacked into protected areas of Harvard's computer network and copied private dormitory ID images.

Harvard did not have a student "Facebook" (a directory with photos and basic information) at the time, although individual houses had been issuing their own paper facebooks since the mid-1980s, and Harvard's longtime Freshman Yearbook was colloquially referred to as the "Freshman Facebook".

Facebook (stylized as facebook) is a for-profit corporation and online social networking service based in Menlo Park, California, United States.

The Facebook website was launched on February 4, 2004 by Mark Zuckerberg, along with fellow Harvard College students and roommates, Eduardo Saverin, Andrew Mc Collum, Dustin Moskovitz, and Chris Hughes.

The founders had initially limited the website's membership to Harvard students; however, later they expanded it to higher education institutions in the Boston area, the Ivy League schools, and Stanford University.Facebook gradually added support for students at various other universities, and eventually to high school students as well.Since 2006, anyone age 13 and older has been allowed to become a registered user of Facebook, though variations exist in the minimum age requirement, depending on applicable local laws.After registering to use the site, users can create a user profile, add other users as "friends", exchange messages, post status updates and photos, share videos, use various applications (apps), and receive notifications when others update their profiles.Additionally, users may join common-interest user groups organized by workplace, school, or other topics, and categorize their friends into lists such as "People From Work" or "Close Friends". Additionally, users can complain about or block unpleasant people.Because of the large volume of data that users submit to the service, Facebook has come under scrutiny for their privacy policies. held its initial public offering (IPO) in February 2012, and began selling stock to the public three months later, reaching an original peak market capitalization of 4 billion.